Running hotspot with "-XX:+UseConcMarkSweepGC -XX:MarkSweepAlwaysCompactCount=0" will crash the VM.

Email from Ramki:

It's because MaxSweepAlwaysCompactCount is used to divide the (serial old) gc count and gives a divide
by zero exception when set to zero. Perhaps the flag should be set to a  minimum value of 1 in
Arguments::check_vm_args_consistency()? If folks agree, could someone file a CR (and
if you prefer i can submit a simple patch).